Which function associated with muscle contraction would be most f=directly affected by low calcium levels?
A) The changing of myosin from the low-energy configuration to the high-energy configuration
B) The formation of cross-bridges between actin and myosin
C) The initiation of an action potential along the surface of the muscle
D) The ability of the muscle to respond to acetylcholine
E) None of the above
- Witty ChiranjitLv 66 years agoFavorite Answer
You should mention the site of low Calcium level. Is it ICF or ECF?
In case of low Ca2+ level in ICF the answer is B) The formation of cross-bridges between actin and myosin.
Crossbridge formation occurs only when Ca2+ binds to Tc i.e. Troponin C & active sites of actin get exposed due to sliding of tropomyosin.
In case of low Ca2+ in ECF the answer can be D) too i.e. the ability of muscle to respond to ACh decreases. Binding of Ca2+ to secretory vesicles containing Ach is necessary for its secretion. When Ca2+ is low, Ach is also less. When Ach is less, less Ach receptors bind to it leading to less entry of Na+.